I pulled my mind out of the swamp it is in this
holiday and reconsidered myposition on the tuber: it may indeed be
an Amchomanes as Christophersuggests and I rejected in my previous
post. I noticed upon further lookingthat there are a few roots
left on it which seem to be as thick as is usualin Anchomanes. I
missed the roots, which are semi-permanent in Anchomanesbut must
have been removed. It is a trifle stupid that the collector made nopicture of the leaf when it was still on the plant, or conveniently
didn'tshow them................